Puberty and upper airway dynamics during sleep.

STUDY OBJECTIVES: The upper airway compensatory response to subatmospheric pressure loading declines with age. The epidemiology of obstructive sleep apnea suggests that sex hormones play a role in modulating upper airway function. Sex hormones increase gradually during puberty, from minimally detectable to adult levels. We hypothesized that the upper airway response to subatmospheric pressure loading decreased with increasing pubertal Tanner stage in males but remained stable during puberty in females. DESIGN: Upper airway dynamic function during sleep was measured over the course of puberty. PARTICIPANTS: Normal subjects of Tanner stages 1 to 5. MEASUREMENTS: During sleep, maximal inspiratory airflow was measured while varying the level of nasal pressure. The slope of the upstream pressure-flow relationship (SPF) was measured. RESULTS: The SPF correlated with age and Tanner stage. However, the relationship with Tanner stage became nonsignificant when the correlation due to the mutual association with age was removed. Females had a lower SPF than males. CONCLUSIONS: In both sexes, the upper airway compensatory response to subatmospheric pressure loading decreased with age rather than degree of pubertal development. Thus, changes in sex hormones are unlikely to be a primary modulator of upper airway function during the transition from childhood to adulthood. Although further studies of upper airway structural changes during puberty are needed, we speculate that the changes in upper airway function with age are due to the depressant effect of age on ventilatory drive, leading to a decrease in upper airway neuromotor tone.

Relationship between REM density, duty cycle, and obstructive sleep apnea in children.

STUDY OBJECTIVES: The pattern and distribution of rapid eye movement (REM) sleep changes during development, yet there have been few studies of REM density in children. Although children with obstructive apnea syndrome (OSAS) obstruct primarily during REM sleep, the relationship between REM density and obstructive apnea has not been established for this population. We hypothesized that (i) REM density and REM cycle duration increases over the course of the night in children, (ii) the duty cycle (inspiratory time divided by respiratory cycle time) increases over the course of the night in children with suspected OSAS, and (iii) the increase in REM density over the course of the night is associated with increased severity of obstructive apnea. DESIGN: REM density and respiratory parameters were measured during polysomnography. SETTING: Sleep laboratory PATIENTS: 76 children with suspected OSAS. INTERVENTIONS: NA MEASUREMENTS AND RESULTS: REM density and the duration of REM cycles increased over the course of the night until the fifth REM cycle, and then stabilized. The duty cycle increased across the first 6 REM cycles. However, the apnea hypopnea index (AHI) did not increase across REM cycles, and was not affected by the changes in REM density or duty cycle. We speculate that the increase in the duty cycle is a compensatory response to increased upper airway loads during sleep, and that this may lead to ventilatory or upper airway muscle fatigue.